Agricultural fungicide

ABSTRACT

Compounds of the formula:   wherein X represents chlorine or bromine, Y represents hydrogen or methyl, and R represents methyl, ethyl or isopropyl, have been found to be effective fungicides.

United States Patent [1 1 Takahashi et al.

[451 Oct. 21, 1975 AGRICULTURAL FUNGICIDE [75] Inventors: Ryohei Takahashi; Isao Yokomichi;

Itaru Shigehara; Terumasa Komyoji, all of Kusatsu, Japan [73] Assignee: Ishihara Sangyo Kaisha Ltd., Osaka,

Japan [22] Filed: Mar. 5, 1974 [21] .Appl. Noi: 448,205

[30] Foreign Application Priority Data OTHER PUBLICATIONS Shriner et al., J. Am. Chem. Soc. 74, 549-550,

(1/20/52). Shaw et 211., Chemical Abstracts, 4n:l l638d, (1953). Hoi et al., J. Med. Chem. 7, 364 366, (5/1964).

Primary Examiner-Norman A. Drezin Attorney, Agent, or Firm-Oblon, Fisher, Spivak, McClelland & Maier [57] ABSTRACT Compounds of the formula:

wherein X represents chlorine or bromine, Y repre sents hydrogen or methyl, and R represents methyl, ethyl or isopropyl, have been found to be effective fungicides.

2 Claims, N0 Drawings AGRICULTURAL FUNGICIDE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an agricultural fungicide 5 NH; CICOR DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The agricultural fungicides of this invention can be prepared by the following reaction:

' NHEOR which effectively inhibits fungi diseases in plants.

2. Description of the Prior Art Various agricultural fungicides are known for preventing diseases in agricultural plants, however, there is a continuing search for fungicides which are more effective than prior art materials, or which are effective for specific utilities. The fungicidal effects of n-propyl- N-(5chloropyridyl-2) carbamate and other n-propyl- N-halopyridyl carbamates have been tested. However, desirable agricultural fungicidal effects were not demonstrated.

SUMMARY OF THE INVENTION X- NH COR wherein X represent chlorine or bromine, Y represents hydrogen or methyl, and R represents methyl, ethyl or isopropyl.

wherein X, Y and R are as defined above. The reaction steps (1) and (3) are performed at reflux temperature e.g. 50-150C. for 0.5-3 hours, preferably about 1 hour, in a solvent, such as benzene, dioxane, xylene, toluene, or the like.

The I-Ialogenation step (2) is performed at 10-50C., preferably 20-30C., by introducing chlorine or bromine gas into a solvent such as acetic acid,

chloroform, etc. I

Having generally described the invention, a more complete understanding can be obtained by reference to certain specific examples, which are included for purposes of illustration only and are not intended to be limiting unless otherwise specified.

The following are typical examples of preparations of pyridylcarbamate compounds according to the invention.

EXAMPLE 1 Preparation of isopropyl N-(S-chloropyridyl-Z) carbamate.

A 3 liter four-necked flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser, was charged with 260 g(2.l2 mole) of isopropylchloroformate and 500 ml of benzene. The temperature of the mixture was kept at 10-20C and a solution of g (1.06 mole) of 2-aminopyridine in benzene was added dropwise to the mixture with stirring. The reaction mixture was kept at room temperature for 1.5 hours with stirring and was refluxed for 1 hour. The reaction mixture was cooled to room temperature and filtered. The filtrate was concentrated to obtain crystals. After recrystallization, 87 g (0.925 mole) of the crystals were dissolved in acetic acid and chlorine gas was introduced at 2530C. for 3 hours with stirring. After the reaction, the reaction mixture was poured into 11 of cold water and aqueous sodium hydroxide was added to adjust the peH to greater than 9 which caused precipitation of crystals.

The crystals were recrystallized from isobutylalcohol to obtain 47.7 g of isopropyl N-(-chloropyridyl-2) carbamate, melting point 141l43C.

EXAMPLE 2 Preparation of ethyl N-(5-bromo-6-methylpyridyl-2) carbamate A 300 ml four-necked flask equipped as in Example 1, was charged with 8.7 g (0.08 mole) of ethylchloroformate and 50 ml of benzene.

A solution of 7.5 g (0.04 mole) of 2-amino-5-bromo- -methylpyridine was added dropwise to the mixture at C with stirring. The reaction mixture was stirred at room temperature for 1.5 hours and then refluxed for 1 hour.

The reaction mixture was cooled to room temperature and filtered. The filtrate was concentrated to obtain crystals. The crystals were recrystallized from isobutyl alcohol to obtain 4.1 g of ethyl N-(5-bromo-6- methylpyridyl-2) carbamate, melting point 102105C.

Exemplary of agricultural fungicides of the pyridylcarbamate type prepared according to this invention are illustrated below, with their melting points.

mate

Fungicidal Test 1 Agar medium containing a specific amount of a predetermined concentration of an active ingredient (C-3) was placed in Petri dishes 9 cm. in diameter. Piricularia oryzae, Pellicularia sasakii or Rhizoctonia salani was inoculated into each medium, cultured at 28-30C for 2 days, and the growth condition of fungi in each Petri dish was observed. The growth of Piricularia oryzaeor Pellicularia sasakii was inhibited at the active ingredient concentration of 6.25 ppm. The growth of Rhizoctonia solani was inhibited at 12.5 ppm.

Fungicidal Test 2 Porcelain pots 9 cm. in diameter were filled with a suitable amount of upland soil and 5 cucumber seeds (grade Hannichi Fushinari) were sowed in each.

Into each pot 1 g of powdered bran in which Rhizoctonia solani was grown was inoculated 2 days after sowing. An aqueous dispersion ml) of a specific concentration of an active ingredient was poured into each pot, and water was poured in at a desirable time. The numbers of cucumber buds, seedlings and normally grown seedlings were observed 6 days after the inoculation, and the rates of the buds, seedlings, and normally grown seedlings were measured.

The results are shown in Table 2.

TABLE 2 (Active ingredient 500 ppm) Growth degree of plant Active Sprouting rate Seedling rate Normally grown ingredient germination seedling rate rate) C-1 90 9O 90 C-2 90 80 C-3 90 90 90 C-5 90 90 C-6 100 100 100 C-7 100 100 100 C-8 100 100 100 C-9 100 100 100 C-lO 100 100 100 Ref. 1 4 0 0 Ref. 2 2 2 O Non-treated 0 O 0 Ref. 1: n-propyl N-(S-chloropyridyl-Z) carbamate Ref. 2: n-pmpyl N-(S-hmmnpyridyl-Z) carbamate Fungicidal Test 3 Fungicidal Test 2 was repeated using lower concentrations of the active ingredients.

The results are shown in Table 3.

TABLE 3 (Active ingredient) 62.5 ppm Growth degree of plant Fungicidal Test 2 was repeated except that the time of application of the active ingredient was changed and the growth degree of the plant was observed 4 days after the inoculation of the fungi. The results are shown in Table 4.

TABLE 4 (Active ingredient 500 ppm) Growth degree of plant Active Inoculation was made the following days ingredient after treatment 1 day 3 days 5 days 7 clays *1 100 100 100 100 C 3 "2 100 80 *3 90 9O 60 80 *1 90 70 60 60 PCNB *2 8O 40 20 40 *3 80 3O 0 30 I sprouting rate (germination rate) 2 seedling rate 3 normally grown seedling rate Fungicidal Test 5 Rice (Grade: Chusei Shinsenbon) was grown in a pot 9 cm in diameter. A specific amount of Pellucularia sasakii grown on oats was inoculated around the roots of the rice seedlings 12 cm. high. After inoculation the pot was placed in a moist chamber at 28C and the next day 10 ml of an aqueous dispersion of a predetermined average lesion length in 2006 average lesion length in non-treated zone Inhibition rate TABLE 5 (Active ingredient l,000 ppm) Active ingredient Inhibition rate C 7 82.9 C 9 100 Non-treated 0 Fungicidal Test 6 Pots 9 cm. in diameter were filled with a suitable amount of soil and cucumber seeds were sowed in each pot. Two days from the sowing, 1 g of powdered bran in which Corticium rolfsii was grown for 10 days at 28C. was inoculated onto each pot. An aqueous dispersion ml) of a predetermined concentration of the active ingredient was poured into each pot and water was poured on at a desirable time. The numbers of cucumber buds, seedlings and normally grown seedlings were observed 6 days after the inoculation.

The growth degree of plant was calculated as in Fungicidal Test 2. The results are shown in Table 6.

tural fungicides. When the active ingredients are applied to plants such as cereals, beans, vegetables, fruits, or the like, which are infected, or may be infected, by a toxic fungi, the active ingredients will impart an excellent fungicidal effect, especially to Piricularia oryzae, Pellicularia sasakii, Rhizoctonia solani and Corticium rolfsii. The inhibition activity of the compounds -of this invention as to Rhizoctonia solam' is very high.

The active ingredient can be used alone or in admixture with an inert carrier, such as talc, kaolin, bentonite, diatomaceous earth, starch, or the like, in a diluted mixture with a liquid diluent, such as water, alcohol, acetone, benzene, or the like. The fungicidal compounds of this invention can be used in the form of an emulsion, dispersion, or wettable powder, by adding a suitable emulsifier, a dispersing agent, an extending agent, or the like. It is also possible to combine these compounds with other fungicides, insecticides, plant growth controlling agents or herbicides to provide synergistic results in some instances. The composition containing the active agent is preferably applied to the seeds before sowing. When the composition in the form of a powder is applied to the seeds, the concentration of the active agent is preferably 10-30 weight The concentration of the active ingredient in any given utility will depend, of course, upon the form of composition, the time of application, the type of toxic fungi etc. and is usually 100-2000 ppm, preferably 200-1000 ppm in liquid form.

m lsopropyl N-(S-chloropyridyl-Z) carbamate 20 wt. parts Zeeklite (finely divided clay) 72 wt. parts Sodium ligninsulfonate 8 wt. parts Fungicidal Test 7 A one nine-hundredths Are pot made of plastic, was filled with a suitable amount of soil. Cucumber, rice, adzuki bean (Japanese), cotton, kidney bean, beet, raddish, and tomato seeds were sowed and 300 ml of an aqueous dispersion of the active ingredient (C-3) having a concentration of 2000 ppm was added. A solution having a concentration of active ingredient of 1000 ppm was poured into each pot on the next day; at suitable times, water was poured into each pot. The growth degree of the plants was observed 12 days and 21 days after the application of the active ingredient. No chemical injury (phytotoxicity) was found.

As is clear from the fungicidal test results, the compounds of this invention impart an excellent fungicidal effect to various fungi which cause plant diseases, without chemical injury (phytotoxicity), in concentrations lower than those required by conventional fungicides. Moreover, the duration of the fungicidal effect is excellent, so that the compounds are desirable as agriculwherein X represents chlorine or bromine and R represents methyl, ethyl, or isopropyl.

2. The compound of claim 1 which is ethyl N-(S- bromo-6-methyl-2 )carbamate. 

1. A COMPOUND OF THE FORMULA:
 2. The compound of claim 1 which is ethyl N-(5-bromo-6-methyl-2)carbamate. 